Lessfs- is available for download.

This version of lessfs comes with slightly improved read performance. Parts of the lessfs_read routine have been reviewed and optimized. A potential race condition has been solved as well.

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5 Responses to Lessfs- is available for download.

  1. Dimitri Bellini says:

    Hi Maru
    thanks for your great work on LessFS, i have tested some other “competitor” like NetApp, DataDomain and ZFS. I have no test read/write performance i have focus on Dedup factor and i saw a very big dedup factor on DataDomain.
    Please i dont want say LessFS have bad Dedup Algorithm but seems very simple because from my simple test it dont found duplicated chunk on simple file.
    What do you think about?
    I’m sorry for my bad english :-)
    Thanks so much

    • maru says:

      Hi Dimitri,

      It’s always interesting to hear about what other dedup solutions are doing. Datadomain uses sliding windows deduplication where lessfs is using fixed blocksize deduplication. I have been hesitating to add sliding windows to lessfs due to patent issues.

      Can you give an example on the dedup ratios that you see on Datadomain and lessfs and what type of data you are testing with?

      Lessfs is known to work very well with raw disk images and when you copy regular files to it. When you use Lessfs to store tar or zip archives then the compression will be low or none since the offsets in the tar archive will differ each time.

      • Dimitri Bellini says:

        Hi Maru
        thanks so much to understand my opinion.
        My test are very simple, i’m working on Mondo Rescue Project Disaster recovery, so we use it to create an image for bare metal restore. I have create some image of few server using the same RHEL release (5.5) with and without compression you can see the file and the size:

        filesys show compression /backup/

        629766144 sdlmoc01-4k_boot-1.iso
        1659176960 sdlmoc01-4k_boot-nocomp-04032011-1.iso
        1165178880 sglvms52-4k_boot-03032011-1.iso
        1092429824 sglvms52-4k_boot-1.iso
        3985399808 sglvms52-4k_boot-nocompressione-07032011-1.iso
        4615309312 sglvms52-4k_boot-nocompressione207032011-1.iso
        Some image are gziped and not but with some file changed inside of it (to the “offset” problem).
        This is the result from DataDomain command:
        Total files: 6; bytes/storage_used: 4.7
        Original Bytes: 13,188,470,376
        Globally Compressed: 4,026,972,574 (dedupped)
        Locally Compressed: 2,807,467,410 (dedupped+compress)
        Meta-data: 13,160,296
        So the sum of all file is like a 12GiB dedupped from DD are only 2,5 GiB!!!Very good performance!!

        Now i show the same file using LessFS:

        [root@sglvms51 mondo-img]# cat /fuse/.lessfs/lessfs_stats
        10 0 0 lessfs_stats
        14 0 0 enabled
        15 0 0 backlog
        20 629766144 110648854 sdlmoc01-4k_boot-1.iso
        21 1659176960 808317386 sdlmoc01-4k_boot-nocomp-04032011-1.iso
        22 1165178880 1034221145 sglvms52-4k_boot-03032011-1.iso
        23 1092429824 976047268 sglvms52-4k_boot-1.iso
        24 3985399808 1378525345 sglvms52-4k_boot-nocompressione-07032011-1.iso
        25 4615309312 239538235 sglvms52-4k_boot-nocompressione207032011-1.iso

        I think “sliding windows” is very useful for many file type, for example as backup storage for Bacula or other Backup software or for simple tar backup.
        Please ask me other info if you need it.
        Many thanks for your great work!!

        • Dimitri Bellini says:

          ops sorry a forget to report the sum from LessFS & DD:

          DataDomain: 2,807,467,410
          LessFS: 4,547,298,233

          LessFs is just more near to 1,6 bigger than DD.

          Many thanks Maru!!

  2. Alex says:


    just to let you know that i still use lessfs, just updated from to, everything run fine on my 32bit systems. The upgraded version allow me to “du” folders faster than before, even on my low performance machines.

    Thank you for your huge work on this project.

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